EP1184847B1 - Dispositif de détection d'oscillation - Google Patents

Dispositif de détection d'oscillation Download PDF

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Publication number
EP1184847B1
EP1184847B1 EP01119844A EP01119844A EP1184847B1 EP 1184847 B1 EP1184847 B1 EP 1184847B1 EP 01119844 A EP01119844 A EP 01119844A EP 01119844 A EP01119844 A EP 01119844A EP 1184847 B1 EP1184847 B1 EP 1184847B1
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EP
European Patent Office
Prior art keywords
wobble
offset voltage
unit
optical disk
tracking
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP01119844A
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German (de)
English (en)
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EP1184847A2 (fr
EP1184847A3 (fr
Inventor
Eiji Pioneer Corporation Nakajima
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Pioneer Corp
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Pioneer Corp
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Publication of EP1184847A3 publication Critical patent/EP1184847A3/fr
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Publication of EP1184847B1 publication Critical patent/EP1184847B1/fr
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
    • G11B7/005—Reproducing
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/007—Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track

Definitions

  • This invention relates to a wobble detecting apparatus for detecting a wobble signal of an optical disk in a device for recording and/or reproducing information for the optical disk.
  • a track 1A of an optical disk 1 on which information is to be stored wobbles.
  • the wobble is detected to reproduce a clock signal at the time of the write.
  • the presence or absence of the wobble is decided to determine whether the optical disk loaded in the device is recordable or dedicated to only reproduction.
  • laser light is focused, the focused light is projected on the optical disk, and the light reflected from the optical disk is received by a light receiving element, thereby providing a wobble signal, a tracking signal, a focus signal and a reproduction signal.
  • Fig. 11 shows relative positions of a light receiving element and a received light spot 21 of the reflected light projected on the light receiving element 4.
  • the light receiving element 4 is partitioned into four sections A, B, C and D.
  • adjustment is made so that the received light spot is projected on the center of the four divided sections. This adjustment cannot be made completely.
  • the optical axis is misaligned leftward, or otherwise, as seen from Fig. 11C, the optical axis is misaligned rightward.
  • the wobble signal is obtained from a difference signal (A + B) - (C + D) on the basis of the output signals from the sections A, B, C and D of the light receiving element 4.
  • US-A-5 764 610 describes an optical disk type identification system using a frequency detector comprising a wobble signal detecting unit sampling the wobble signal using the signal output by a light pickup.
  • a system control circuit outputs a switching signal to a switch which selects one of the input signals produced by rotation control circuits before supplying it to the spindle motor rotating the disk.
  • An object of this invention is to provide a wobble signal detecting apparatus which can detect the presence or absence of a wobble.
  • Fig. 1 is an arrangement view of a first embodiment of this invention
  • Fig. 2 is a block diagram showing an example of a wobble detecting unit
  • Figs. 3 and 4 are flowcharts for explaining the operation of the first embodiment of this invention.
  • reference numeral 1 denotes an optical disk; 2 a carriage; 2A an actuator on which an objective lens for focusing laser light on the optical disk 1 is loaded; 3 a driver for driving the actuator; 4 a light receiving element; 5 a matrix circuit; 6 a focus control unit; 7 a tracking control unit; 8 an actuator switch; and 9 an adder unit.
  • the matrix circuit 5 produces an RF signal of A+B+C+D based on the output signals from the four divided sections A, B, C and D of the light receiving element 4, and also creates e.g. (phase difference between the RF signal and the output signal A) + (phase difference between the RF signal and the output signal D) - (phase difference between the RF signal and the output signal B) - (phase difference between the RF signal and the output signal C) which is to be supplied to the tracking control unit 7. Namely, tracking is executed by the DPD (Differential Phase Detection) technique.
  • the recording and/or reproducing apparatus creates the signal (A+D-B-C) to be supplied to the focus control unit 6, thereby executing the focus control.
  • the actuator 2A is moved according to a control voltage applied to the driver 3. For example, if the control voltage is positive, the actuator 2A moves by a prescribed distance toward the inner periphery of the optical disk 1, whereas if the control voltage is negative, the actuator 2A moves by the prescribed distance toward the outer periphery of the optical disk 1.
  • the actuator 2A is loaded on the carriage 2 by e.g. spring. During the tracking, the actuator 2A follows a track to move. When the actuator 2A moves by a prescribed distance, the carriage 2 moves toward the outer periphery and then the actuator 2A is located on the center of the carriage 2.
  • the above operation is the same as that of the conventional device for recording and reproducing information on and from the optical disk.
  • reference numeral 10 denotes a wobble detecting unit; 11 an offset voltage generating unit; 12 a control unit; 13- 15 an interface (I/O) ; and 16 a processor (CPU).
  • a difference signal (A+B) - (C+D) from the light receiving element 4 is converted into a square wave by a binary-digitizing circuit 10B through a band-pass filter (BPF) 10A passing a wobble signal frequency.
  • BPF band-pass filter
  • a wobble deciding circuit 10C decides that if a subsequent pulse is successively produced within a prescribed time after a certain pulse is produced from the binary-digitizing circuit 10B, there is a wobble, and if the subsequent pulse is not successively produced, there is no wobble.
  • step S1 is first executed.
  • step S1 the control unit 12 turns on the actuator switch 8 to start the tracking operation.
  • step S2 the control unit 12 determines whether or not a wobble has been detected by the wobble detecting unit 10. If YES, the processing proceeds to step S3. In step S3, the control unit 12 produces an output indicative of that the wobble has been detected. The processing is ended.
  • step S2 the processing proceeds to step S4.
  • step S4 the control unit 12 instructs the offset voltage generating unit 11 to generate a positive prescribed offset voltage (+V).
  • the prescribed offset voltage (V) is set at a voltage which causes the actuator 2A to move by e.g. about 10 ⁇ m.
  • the positive offset voltage thus generated is supplied to the adder unit 9 through the I/O 14. It is added to the tracking control voltage produced from the tracking control unit 7. The resultant voltage is entered into the driver 3.
  • the driver 3 When the positive offset voltage (+V) is entered into the driver 3, the driver 3 causes the actuator 2A to move toward e.g. the inner periphery of the optical disk 1.
  • step S5 the control unit 12 determines whether or not the wobble has been detected by the wobble detecting unit 10. If YES, the processing proceeds to step S3. In step S3, the control unit 12 confirms that the wobble has been detected. The processing is ended.
  • step S5 the processing proceeds to step S6.
  • step S6 the control unit 12 determines whether or not the prescribed voltage has been generated by a prescribed number of times. If NO in step S6, the processing proceeds to step S7.
  • step S7 the control unit 12 instructs the offset voltage generating unit 11 to generate a voltage resulting from addition of the prescribed voltage (+V) to the offset voltage (+V) which is being generated, thus generating an offset voltage of +nV (n: number of generation times) .
  • steps S4 - step S7 are repeated.
  • Step S8 Steps S8 to S11 are executed.
  • step S8 the control unit 12 instructs the offset voltage generating unit 11 to generate a negative prescribed offset voltage (-V) .
  • -V negative prescribed offset voltage
  • step S10 If it is determined in step S10 that the prescribed negative voltage has been generated by the prescribed number of times, the processing proceeds to step S12. In step S12, the control unit 12 produces an output indicative of that no wobble has been detected. The processing is ended.
  • FIG. 5 is an arrangement view of the second embodiment of this invention
  • Fig. 6 is a flowchart of the operation of the second embodiment of this invention.
  • a carriage control unit 7A, a carriage switch 8A and an I/O 17 are added to the arrangement of the first embodiment explained referring to Fig. 1.
  • step S21 the control unit 12 turns OFF the actuator switch 8 and in step S22, the control unit 12 turns OFF the carriage switch 8A.
  • step S23 the control unit 12 instructs the offset voltage generating unit 111 to generate an offset voltage (+Vo).
  • the positive offset voltage thus generated is supplied to the adder unit 9 through the I/O 14.
  • the actuator 2A moves by e.g. 80 ⁇ m toward the inner periphery of the optical disk 1.
  • step S24 the control unit 12 turns ON the actuator switch 8.
  • the actuator switch 8 is turned ON and the carriage switch 8A is turned OFF, the actuator 2A moves from the inner periphery to the outer periphery as the optical disk 1 rotates, thus generating the misalignment of the optical axis.
  • step S25 the control unit 12 determines whether or not a wobble has been detected by the wobble detecting unit 10. If YES, the processing proceeds to step S26. The control unit 12 produces an output indicative of that the wobble has been detected. The processing is ended.
  • step S25 If NO in step S25, i.e. no wobble has been detected, the processing proceeds to step S27.
  • step S27 the control unit 12 counts the number of times of rotation of the optical disk 1 on the basis of the rotation information of the optical disk 1 supplied through the I/O 17 to determine whether or not the counted value has reached a prescribed number of times. If NO, the processing reverts to step S25. The processing of steps S25 to S27 is repeated.
  • step S28 If YES, i.e. the counted value has reached the prescribed number of times, the processing proceed to step S28. The processing is ended.
  • the actuator 2A is moved toward the inner periphery of the optical disk by superposition of the offset voltage (+V). This is because it is not clear in which state of Fig. 11A and Fig. 11C, the misalignment of the optical axis is when detection of the wobble is started.
  • the actuator switch 8 When the actuator switch 8 is turned ON and the carriage switch 8A is turned OFF, as described above, as the optical disk 1 rotates, the actuator 2A moves from the inner periphery of the optical disk to the outer periphery thereof.
  • the misalignment of the optical axis is in the state of Fig. 11C, the misalignment is corrected as the actuator 2A moves toward the outer periphery so that the present state approaches the state of Fig. 11B.
  • step S23 the offset voltage (+V) is generated to move the actuator 2A toward the inner periphery by e.g. 80 ⁇ m so that the optical axis is in the state of Fig. 11C. Further, the actuator 2A is moved as the optical disk 1 rotates. Thus, the state of the optical axis approaches the state with no misalignment as shown in Fig. 11B.
  • step S27 the prescribed number of times of rotation in step S27 is set at 160.
  • Fig. 7 is an arrangement view of the third embodiment of this invention.
  • Fig. 8 is a flowchart of the operation of the third embodiment of this invention.
  • a low pass filter (LPF) 18 for passing a DC component and I/O 19 are added to the arrangement of the first embodiment of this invention as shown in Fig. 1.
  • step S31 the control unit 12 turns OFF the actuator switch 8 through the I/O 13.
  • step S32 the control unit 12 reads the output value from the LPF 18 through the I/O 19.
  • step S33 the control unit 12 determines whether or not the output value from the LPF 18 is 0 ⁇ ⁇ ( ⁇ is an error providing a negligible influence on the wobble detection). If YES, the processing proceeds to step S37.
  • step S34 the control unit 12 determines whether or not the output from the LPF 18 is negative or positive. If positive, in step S35, the control unit 12 instructs the offset voltage generating unit 11 to generate an offset voltage which increases by an amount corresponding to the absolute value of the output value of the LPF 18 in a direction from 0 to negative and add the generated offset voltage to the adder unit 9 through the I/O 14. Further, the processing reverts to step S32. The processing from step S32 to S25 is repeated until the decision of step S33 becomes YES.
  • step S34 the processing proceeds to step S36.
  • step S35 the control unit 12 instructs the offset voltage generating unit 11 to generate an offset voltage which increases by an amount corresponding to the absolute value of the output value of the LPF 18 in a direction from 0 to positve and add the generated offset voltage to the adder unit 9 through the I/O 14. Further, the processing reverts to step S32. The processing from step S32 to S35 and S36 is repeated until the decision of step S33 becomes YES.
  • step S33 if YES, i.e., the output from the LPF 18 becomes 0 ⁇ ⁇ , the processing proceeds to step S37.
  • step S37 the control unit 12 turns ON the actuator switch 8.
  • step S38 the control unit 12 determines whether or not a wobble has been detected by the wobble detecting unit 10. If YES, the control unit 12 produces an output indicative of that the wobble has been detected. If NO, the control unit 12 produces an output indicative of that no wobble has been detected. Thus, the processing is ended.
  • the offset voltage corresponding to the absolute value of the LPF output value is generated.
  • the relationship between the LPF output value and the offset value to be added for its correction differs according to the characteristic of an optical system of a product. Therefore, the conversion coefficient from the LPF output value in each product into the offset voltage may be previously set.
  • step S33 if the output from the LPF 18 is within a permissible range of 0 ⁇ ⁇ , the processing proceeds to step S37.
  • step S37 the control unit 12 turns OFF the actuator 8 to detect the wobble. This reason will be explained referring to Fig. 9.
  • Figs. 9A, 9B and 9C show relative positions of the light receiving element 4 and the light received spot.
  • Figs. 9D, 9E and 9F shows a waveform of a difference signal A+B-C-D produced from the matrix circuit 5 when the optical disk 1 is rotated once with the actuator switch 8 being in the OFF state.
  • the matrix circuit 5 produces the difference signal A+B-C-D as shown in Fig. 9E, i.e. a sinusoidal difference signal whenever the spot of the laser light projected on the optical disk 1 crosses a track.
  • the DC component thereof is zero.
  • the offset voltage is generated from the offset voltage generating unit 11 to move the actuator 2A so that the state of Fig. 9A or 9C is shifted into the state of Fig. 9B with no misalignment of the optical axis, in step S37, the actuator switch 8 is turned ON, and in step S38, the wobble is detected.
  • the polarity and amount of the generated offset voltage can be known from the polarity and absolute value of the output of the LPF 18. Therefore, the offset voltage is generated, and when the output for the LPF 18 is 0 ⁇ ⁇ , the actuator switch 8 is turned ON to detect the wobble. In this way, the wobble can be detected in a short time.

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  • Optical Recording Or Reproduction (AREA)

Claims (5)

  1. Dispositif de détection de wobble pour un appareil d'enregistrement et/ou de reproduction d'information sur un disque optique (1), comprenant:
    une unité de détection de wobble (10) pour détecter un wobble sur la base d'un signal d'un élément de réception de lumière (4) qui reçoit de la lumière réfléchie par le disque optique (1),
    caractérisé en ce que
    ledit dispositif de détection de wobble comprend en outre:
    une unité de génération de tension d'offset (11) pour générer une tension d'offset,
    une unité d'ajout (9) pour ajouter ladite tension d'offset à un signal de commande de poursuite appliqué à un actionneur de poursuite (2A) pour le disque optique (1),
    un interrupteur d'actionneur de poursuite (8) pour commander l'application, oui ou non, dudit signal de commande de poursuite au dit actionneur de poursuite (2A), et
    une unité de commande (12) destinée à activer ledit actionneur de poursuite (2A) pour la détection d'un wobble et décider si, oui ou non, le wobble a été détecté par ladite unité de détection de wobble (10),
    dans lequel ladite unité de commande (12) est adaptée pour entraîner ladite unité de génération de tension d'offset (11) à générer une tension prédéterminée positive (+V) ou négative (-V), dans le cas où le wobble n'a pas été détecté,
    et ladite unité de commande (12) est en outre adaptée pour décider, après que ladite tension prédéterminée a été ajoutée au signal de commande de poursuite appliqué au dit actionneur de poursuite (2A), si, oui ou non, le wobble a été détecté par ladite unité de détection de wobble (10).
  2. Ledit dispositif de détection de wobble selon la revendication 1, dans lequel ladite unité de commande (12) est adaptée pour entraîner ladite unité de génération de tension d'offset (11) à générer une nouvelle tension d'offset de ladite tension prédéterminée (+V ou -V) plus la tension d'offset produite précédemment, si le wobble n'a pas été détecté par l'unité de détection de wobble (10) quand ladite tension prédéterminée positive (+V) ou négative (-V) est générée par ladite unité de génération de tension d'offset (11), entraînant ainsi l'unité de détection de wobble (10) à répéter la détection du wobble un nombre prédéterminé de fois (n).
  3. Dispositif de détection de wobble pour un appareil d'enregistrement et/ou de reproduction d'information sur un disque optique (1), comprenant:
    une unité de détection de wobble (10) pour détecter un wobble sur la base d'un signal d'un élément de réception de lumière (4), qui reçoit de la lumière réfléchie par le disque optique (1),
    caractérisé en ce que
    ledit dispositif de détection de wobble comprend en outre:
    une unité de génération de tension d'offset (11) pour générer une tension d'offset,
    une unité d'ajout (9) pour ajouter ladite tension d'offset à un signal de commande de poursuite appliqué à un actionneur de poursuite (2A) pour le disque optique (1),
    un interrupteur d'actionneur de poursuite (8) pour commander l'application, oui ou non, dudit signal de commande de poursuite au dit actionneur de poursuite (2A),
    un interrupteur de chariot (8A) pour commander l'application, oui ou non, d'un signal de commande à un chariot (2) sur lequel ledit actionneur de poursuite (2A) est chargé, et
    une unité de commande (12) pour activer ledit interrupteur de chariot (8A), activant ainsi ledit actionneur de poursuite (2A) pour la détection de wobble,
    ladite unité de commande (12) est adaptée pour entraîner ladite unité de génération de tension d'offset (11) à générer une tension prédéterminée,
    et ladite unité de commande (12) est en outre adaptée pour procéder, après que la tension prédéterminée a été ajoutée au dit signal de commande de poursuite appliqué au dit actionneur de poursuite (2A), à décider si, oui ou non, le wobble a été détecté par ladite unité de détection de wobble (10).
  4. Ledit dispositif de détection de wobble selon la revendication 3, dans lequel ladite unité de commande (12) est adaptée à compter le nombre de rotations du disque optique (1) à partir du moment où la détection du wobble a commencé, et à confirmer la non-détection du wobble si le wobble n'a pas été détecté lorsque la valeur comptée atteint un nombre de tours prédéterminé.
  5. Dispositif de détection de wobble pour un appareil d'enregistrement et/ou de reproduction d'information sur un disque optique (1), comprenant:
    une unité de détection de wobble (10) pour détecter un wobble sur la base d'un signal d'un élément de réception de lumière (4), qui reçoit de la lumière réfléchie par le disque optique (1),
    un filtre passe-bas (18) pour faire passer une composante DC d'un signal différentiel produit par ledit élément de réception de lumière (4),
    caractérisé en ce que
    ledit dispositif de détection de wobble comprend en outre:
    une unité de génération de tension d'offset (11) destinée à générer une tension d'offset,
    une unité d'ajout (9) pour ajouter ladite tension d'offset à un signal de commande de poursuite appliqué à un actionneur de poursuite (2A) pour le disque optique (1),
    un interrupteur d'actionneur de poursuite (8) pour commander l'application, oui ou non, dudit signal de commande de poursuite au dit actionneur de poursuite (2A), et
    une unité de commande (12) pour désactiver ledit actionneur de poursuite (2A) pour la détection du wobble,
    et dans lequel ladite unité de commande (12) et adaptée pour entraîner ladite unité de génération de tension d'offset (11) à générer ladite tension d'offset de telle manière qu'une sortie dudit filtre passe-bas (18) est zéro, à activer ledit interrupteur d'actionneur de poursuite (8), lorsque la sortie dudit filtre passe-bas (18) est devenue approximativement zéro, et a décider si, oui ou non, le wobble a été détecté par ladite unité de détection de wobble (10).
EP01119844A 2000-08-23 2001-08-16 Dispositif de détection d'oscillation Expired - Lifetime EP1184847B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2000252324 2000-08-23
JP2000252324A JP4012673B2 (ja) 2000-08-23 2000-08-23 ウォーブル検出装置

Publications (3)

Publication Number Publication Date
EP1184847A2 EP1184847A2 (fr) 2002-03-06
EP1184847A3 EP1184847A3 (fr) 2004-07-07
EP1184847B1 true EP1184847B1 (fr) 2006-10-18

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EP01119844A Expired - Lifetime EP1184847B1 (fr) 2000-08-23 2001-08-16 Dispositif de détection d'oscillation

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US (1) US6751172B2 (fr)
EP (1) EP1184847B1 (fr)
JP (1) JP4012673B2 (fr)
DE (1) DE60123896T2 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002279640A (ja) 2001-03-21 2002-09-27 Ricoh Co Ltd ウォブル検出回路とその装置
JP3566690B2 (ja) 2001-12-07 2004-09-15 株式会社リコー ウォブル信号検出回路及び光ディスク装置
TW200601302A (en) * 2004-06-30 2006-01-01 Lite On It Corp Method of controlling a focusing point on an optical disc
TWI346953B (en) * 2007-06-26 2011-08-11 Quanta Storage Inc Apparatus and method for calibrating focus balance in an optical disk drive

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4866688A (en) * 1985-12-20 1989-09-12 Hitachi, Ltd. Composite tracking servo system for optical disc apparatus with track offset correction
JP2788022B2 (ja) * 1995-02-14 1998-08-20 株式会社日立製作所 光記録媒体
US5896365A (en) * 1995-04-28 1999-04-20 Canon Kabushiki Kaisha Optical information recording medium capable of recording in lands and grooves without a track-jumping operation; optical information recording/reproducing apparatus using, and master disk exposure apparatus for producing the same
JP3707835B2 (ja) * 1995-08-10 2005-10-19 株式会社東芝 光ディスク装置
JPH09198779A (ja) * 1996-01-18 1997-07-31 Pioneer Electron Corp ディスク判別装置
KR19990016488A (ko) * 1997-08-16 1999-03-05 구자홍 트랙킹 제어 장치 및 그 방법

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Publication number Publication date
JP4012673B2 (ja) 2007-11-21
JP2002074661A (ja) 2002-03-15
DE60123896T2 (de) 2007-02-15
US6751172B2 (en) 2004-06-15
EP1184847A2 (fr) 2002-03-06
DE60123896D1 (de) 2006-11-30
EP1184847A3 (fr) 2004-07-07
US20020024897A1 (en) 2002-02-28

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